I haven't read the Fascist Decalogue, but I read a biography of him and a study of Italy under Fascism.
Mussolini was very intelligent - he spoke 4 languages, was a gifted orator, and a master of the new forms of propaganda. He was also a bit of an environmentalist in that he promoted reforestation.
He was much less murderous than Hitler, and preferred to blackmail his opponents rather than send them to prison. If you look at the number of judicial executions in Italy and the USA from 1921-1945, you'll see that the USA had far more judicial executions.
On the other hand, Mussolini was a snake who betrayed everyone around him and who had a very inflated sense of his own worth - in other words, he was a narcissist. He was incompetent as a commander in chief and led Italy down the path of destruction.